West Nile buzzes into state

News-Times, The (Danbury, CT)

Published 8:00 pm, Tuesday, July 11, 2006

Theodore Andreadis
, an entomologist with the
Connecticut Agricultural Experiment Station
in New Haven, said Tuesday that researchers found virus-infected mosquitoes June 29 in West Haven.
Andreadis - who has tracked West Nile in Connecticut since it first appeared in 1999 - said that's the earliest detection of the virus on record in the state. Normally, the virus manifests itself in mid-July.
"They've already found it in Massachusetts and Staten Island,'' Andreadis said. "So it's throughout the region.''
Andreadis' team has also found far more mosquitoes at the 91 traps it maintains in the state than in years past.
This is probably due to the weather in June, when the state got more than twice its normal rainfall. The Danbury area got nearly 9 inches of rain in June; the average is about 4 inches.
That means there is more standing water, providing more breeding ground for mosquitoes, which carry the virus between birds and people.
"We've kind of reached a plateau now, but a couple of weeks ago, (the number of mosquitoes) was off the charts,'' Andreadis said.
With the rainy seasons ended, summer temperatures will turn hot and humid. Mosquitoes are more active in hot weather.
Given all these factors, Andreadis said, it makes common sense to start thinking about West Nile virus affecting more humans in Connecticut and earlier in the year.
"I don't want to be a forecaster,'' he said. "But the conditions this year are ripe.''
"He could be right,'' said
Dave Daigle
, a spokesman for the infectious diseases division of the
Centers for Disease Control and Prevention
. "We always say the local guys know best about what's happening in their area.''
Daigle said 28 states have reported West Nile virus activity in 2006.
All of the 48 contiguous states have had West Nile activity of some sort since the epidemic began in 1999 with a cluster of cases in New York City.
Since then, West Nile virus has spread north, south and west to become the most common mosquito-borne illness in North America.
Birds act as winged pool of infection, carrying the virus from place to place. Mosquitoes spread the virus from bird to bird, then from birds to humans.
Most of the time, human who are infected with the virus get mild symptoms - a fever, headache and aching joints that go away after a few days.
For a select number of people - infants, seniors, and people with compromised immune systems - the virus is far more dangerous, causing a polio-like paralysis, chronic fatigue, encephalitis, and in rare cases, death.
Since 1999, there have been about 20,000 reported cases of West Nile infection in the United States and about 785 deaths. In Connecticut, there have been a total of 48 cases and two deaths.
In Connecticut, the number of human cases peaked at 17 in both 2002 and 2003. In 2004, there was only one case, giving rise to hope the virus was on the wane.
But in 2005, there were six cases, including the state's second fatality.
Andreadis' research has shown that, despite the large number of crows killed by West Nile in the first years of the outbreak, a far less foreboding bird - the American robin - acts as the main reservoir of the virus in the state.
"We've stopped collecting dead birds in the state for West Nile, because we're no longer getting meaningful numbers,'' Andreadis said.
"In 2002 and 2003, we were seeing about 4,000 dead birds a year with the virus. In 2005, it was 200. We don't know the reason for that. It may be the birds have developed immunity to the virus.''
He's also found that one species of mosquitoes, Culex pipiens, is most responsible for carrying the virus from bird to bird, while another species, Culex salinarius, spreads in from birds to humans.
"It's a more aggressive human biter,'' he said about Culex salinarius.
After tracking the disease from year to year, Andreadis said public health officials now know it is most prevalent in the late summer - from mid-August to late September.
It's also found more often in the state's shoreline towns than in its interior.
"We know the coastal towns in Fairfield and New Haven counties are the hot spot, and Litchfield and Tolland counties are least likely,'' he said.
The best way for people to avoid West Nile infection is to avoid mosquito bites. That means not exercising at dawn or dusk - when mosquitoes are most active - and wearing protective clothing or insect repellent, especially repellent with DEET.
To help control the number of mosquitoes, many municipalities use a larvicide to kill mosquito larvae that might be growing in catch basins.
Scott Leroy
, Danbury's health director, said the city did this recently.
But because of the early start to this year's West Nile season, and the large number of mosquitoes he's seen, Andreadis said this year may hold some surprises.
"In 2003, we had a very wet summer,'' he said. "That year, we had 17 human cases and they were everywhere in the state. The potential for the same kind of year is there.''